Adsorption.svg thumb Brunauer, Emmett and Teller s Adsorption BET model of multilayer adsorption is a random distribution of molecules on the material surface. Adsorption is the adhesion of atoms , ions ... absorption chemistry work Memidex WordNet Dictionary Thesaurus accessdate 2010 11 02 ref Note that adsorption ... sorption encompasses both processes, while desorption is the reverse of adsorption. It is a surface phenomenon . Similar to surface tension , adsorption is a consequence of surface energy . In a bulk ... involved, but the adsorption process is generally classified as physisorption characteristic ... model systems with superplasticizers investigated by atomic force microscopy, zeta potential, and adsorption ... Plank first4 J. doi 10.1016 j.jcis.2010.03.005 pmid 20356605 ref Adsorption is present in many natural ... process requirements adsorption chillers , synthetic resins , increase storage capacity of carbide derived carbons for tunable nanoporous carbon , and water purification . Adsorption, ion exchange ... exposure to specific drugs or parts thereof. Isotherms Adsorption is usually described through ... is uniform, that is, all the adsorption sites are equivalent. Adsorbed molecules do not interact. All adsorption occurs through the same mechanism. At the maximum adsorption, only a monolayer ... microporous surfaces. The Langmuir isotherm is nonetheless the first choice for most models of adsorption ... . Langmuir suggested that adsorption takes place through this mechanism math A g S rightleftharpoons AS math , where A is a gas molecule and S is an adsorption site. The direct and inverse ... of the adsorption sites occupied, in the equilibrium we have math K frac k k 1 frac theta ... to the number of adsorption sites through the ideal gas law . If we assume that the number of sites ... A sub 2 sub S A sub g sub A sub 2 sub S unicode A sub 3 sub S and so on image Adsorption Isotherms ... heats of adsorption for all layers except the first are equal to the heat of condensation ... more details
Orphan date February 2009 Supercritical Adsorption also referred to as the adsorption of supercritical fluid s, is the adsorption at above critical temperatures. There are different tacit understandings ... T c math is the critical temperature History Observations of supercritical adsorption reported before ... in supercritical adsorption research under the impetus of the quest for clean alternative fuel s has been observed. Considerable progress has been made in both adsorption measurement techniques and Molecular modelling molecular simulation of adsorption on computers, rendering new insights into the nature of supercritical adsorption. Properties According to the adsorption behavior, the adsorption ... adsorption. Isotherms in the second region will show the feature of mechanism transition. Isotherms in the third region will show the feature of supercritical adsorption. The transition will take ... type, such as adsorption on Microporous material microporous activated carbon . However, discontinuous ... types, such as adsorption on Mesoporous material mesoporous silica gel . The decisive factor in such a classification of adsorption is merely temperature, irrespective of pressure. This is because ... of the pressure applied. This fundamental law determines the different adsorption mechanism for the subcritical ... of adsorption is the saturation pressure math P s math of adsorbate . Beyond math P s math condensation happens. Adsorbate in the adsorbed phase is largely in liquid state, based on which different adsorption ... adsorption isotherms An adsorption isotherm depicts the relation between the quantity adsorbate and the bulk ... adsorption equilibrium. Such equilibrium data are required for optimal design of process relying on adsorption and are considered fundamental information for theoretical studies. 1. Measurement of Gas Solid Adsorption Equilibriums Volumetric Method Image Supercritical adsorption figure1.jpg ... days of adsorption studies by Langmuir, Dubinin and others. It basically comprises a gas expansion ... more details
Cryo adsorption is a method used for hydrogen storage where gaseous hydrogen at cryogenic temperatures 150 60 K is physically adsorbtion adsorbed on porous material, mostly activated carbon . The achievable storage density is between liquid hydrogen LH sub 2 sub storage systems and compressed hydrogen CGH sub 2 sub storage systems ref http www.hyweb.de Knowledge Ecn h2a.html Cryo Adsorption ref . See also Hydrogen tank Hydrogen economy References reflist External links http ads.ari.uni heidelberg.de abs 2006APS..MARH16004A Hydrogen cryo adsorption comparing low pressure and isosteric heats Category Chemical engineering Category Cryogenics Category Hydrogen technologies Category Hydrogen storage es Crioadsorci n ... more details
Unreferenced date February 2007 Orphan date December 2007 Selective adsorption is the effect when minima associated with bound state bound state resonance s occur in specular intensity in atom surface scattering . It was first observed in 1930 by Theodor Estermann Estermann and Otto Stern Stern . Starting from the 1970s, selective adsorption has been extensively studied, both theoretically and experimentally. It is a powerful tool to determine the gas surface interaction potential by yielding the vibrational energy spectrum of the gas atom bound to the surface. Energy level s measured with this technique are available for many systems. Category Surface chemistry Category Physics Physics stub ... more details
Adsorption is the adhesion of ions or molecules onto the surface of another phase. ref name text1 cite ... 2 chapter Adsorption ref Adsorption may occur via physisorption and chemisorption . Ion s and molecule ... composed of repeating subunits bound together by covalent bond s. The adsorption of ions and molecules ... spectroscopy. ref name Handbook Adsorption isotherms The adsorption process can be characterized by determining ... experimentally by the construction of an adsorption isotherm. An adsorption isotherm is a graph ... ref name SpecialChem Adsorption and charge relationship File 11115.png thumb The structure of sodium ... have different side chains on their monomers that can become charged due to the adsorption or dissociation ... its surface depends on energies of interaction, thermodynamics of adsorption can be used to understand the driving forces for adsorption. To measure the thermodynamics of polymer surfaces, contact angle ... functional groups across all areas of the surface. Because of this, adsorption of molecules onto ... equation states that for the adsorption of a molecule of adsorbate A onto a surface binding ... coverage fraction, 0 is empty, 1 is fully covered math k ad math is the adsorption equilibrium constant Adsorption energy Because many polymers are composed of primarily of hydrocarbon chains with at most ... to development of useful technologies. The Gibbs energy of adsorption, math Delta G ad math , can be determined from the adsorption equilibrium constant ref name text1 math Delta G ad RTln K ad math ... nref3 Experimentally, the enthalpy and entropy of adsorption are often used to fine tune the adsorption properties of a material. The enthalpy of adsorption can determined from constant pressure calorimetry ... H ad math is the integral molar enthalpy of adsorption math N math is the number of moles adsorbed. From the enthalpy of adsorption, the entropy of adsorption can be calculated math Delta S ad frac Delta H ad T math where math Delta S ad math is the integral molar entropy of adsorption math T math is the temperature ... more details
Adsorption not to be mistaken for Absorption chemistry absorption is the accumulation and adhesion of molecules .... The adsorption of larger biomolecules such as proteins is of high physiological relevance, and adsorb ... behind protein adsorption include surface energy, intermolecular forces, hydrophobicity, and ionic or electrostatic interaction. By knowing how these factors affect protein adsorption, they can ... of surface roughness on protein adsorption url http phys.au.dk fileadmin site files publikationer ... to encourage adsorption of specific proteins, fibrous capsule formation, and wound healing. This would ... replacement necessitates integration with the host tissues, and protein adsorption facilitates this integration ... methods. However, in some cases, protein adsorption to biomaterials can be an extremely unfavorable ..., and protein adsorption would hinder their effectiveness. Fundamentals of Protein Adsorption Proteins ... , protein adsorption is a critical phenomenon that describes the aggregation of these molecules ... Energy of Protein Adsorption The fundamental idea behind spontaneous protein adsorption is that adsorption ... SI unit joule per kelvin H is the enthalpy SI unit joule In order for the protein adsorption ... adsorption are 1 ionic or electrostatic interaction, 2 hydrogen bonding , 3 hydrophobic interaction .... Thus, hydrogen bonding does not have a strong stabilizing effect on protein adsorption in an aqueous ... Adsorption in Aqueous Media journal Pure Applied Chemistry year 1979 volume 51 pages 1549 1559 ref Rate of Adsorption In order for proteins to adsorb, they must first come into contact with the surface ... to a solid surface. Under conditions of low flow and minimal temperature gradients, the adsorption ... diffusion, and these must be considered in the rate of protein adsorption. Flow in a thin channel ... of the channel This equation ref name Dee is especially applicable to analyzing protein adsorption to biomedical devices in arteries, e.g. stents . Protein Adsorption to Metals Chemical composition ... more details
Adsorption of polyelectrolytes on solid substrates is a surface phenomenon where long chained polymer molecules with charged groups dubbed polyelectrolytes bind to a surface that is charged in the opposite polarity. On the molecular level, the polymers do not actually bond to the surface, but tend to stick to the surface via intermolecular forces and the charges created by the dissociation of various side groups of the polymer. Because the polymer molecules are so long, they have a large amount of surface area with which to contact the surface and thus do not desorb as small molecules are likely to do. This means that adsorbed layers of polyelectrolytes form a very durable coating. Due to this important ... & Co. location Weinheim pages 226 228 ref Kinetics of Layer Formation Models for the adsorption behavior ... of Polyelectrolyte Adsorption However, the general character of the process can be reasonably well ... title Adsorption of polyelectrolytes and inter colloidal forces journal Physica A year 1998 volume ... lambda B frac e 2 4 pi varepsilon 0 varepsilon r k B T , math Layer by Layer Adsorption File Layer by Layer Adsorption.jpg right thumb 280px A simple schematic showing the alternating adsorption of positively ... in polyelectrolyte adsorption, initial rates of adsorption of polyectrolytes to charged surfaces are often ... drawing more polyelectrolyte chains to the surface. This drop in adsorption rates can be countered ... of polyelectrolyte adsorption is greatly affected by the contents of the solution and by the quality ... the solvent affects the adsorption characteristics of the surface polymer interface is due to the dielectric ... of the major applications of polyelectrolyte adsorption is the stabilization or destabilization .... The adsorption of polyelectrolytes can be used to stabilize the suspension, such as in the case ... stabilized by surfactants , and oftentimes ionic surfactants, the adsorption of the multilayer ... Polyelectrolyte Adsorption Category Materials science ... more details
. Pollutant Contacting and Adsorption Polluted effluent is added into the bottom of the cell and mixed with the adsorbent in the adsorption zone 1.1 where adsorption of the pollutants ... the adsorbent surface restoring its full adsorptive capacity completing the adsorption regeneration ... more details
Sodium adsorption ratio SAR is a measure of the suitability of water for use in agricultural irrigation , as determined by the concentrations of solids dissolved in the water. It is also a measure of the sodicity of soil, as determined from analysis of water extracted from the soil. The formula for calculating sodium adsorption ratio is SAR Na sup sup Ca sup 2 sup Mg sup 2 sup 2 sup 1 2 sup where sodium , calcium , and magnesium are in milliequivalents liter. Although SAR is only one factor in determining the suitability of water for irrigation, in general, the higher the sodium adsorption ratio, the less suitable the water is for irrigation. Irrigation using water with high sodium adsorption ratio may require soil amendments to prevent long term damage to the soil. If irrigation water with a high SAR is applied to a soil for years, the sodium in the water can displace the calcium and magnesium in the soil. This will cause a decrease in the ability of the soil to form stable aggregates and a loss of soil structure and tilth. This will also lead to a decrease in infiltration and permeability of the soil to water leading to problems with crop production. See also Alkaline soil External links http www.ag.ndsu.edu pubs plantsci soilfert eb57 1.htm North Dakota State University Salinity and sodicity in North Dakota soils Retrieved 24 December 2008. http cahedev.nmsu.edu pubs a a 116.pdf New Mexico State University Irrigation water classification systems PDF file retrieved 24 December 2008. Category Water quality indicators ... more details
Image Langmuir Adsorption Model.jpg thumb 400px right Fig 1. An schematic showing equivalent sites, occupied blue and unoccupied red clarifying the basic assumptions used in the model. The adsorption sites ... The Langmuir adsorption model is the most common model used to quantify the amount of adsorbate adsorption adsorbed on an adsorbent as a function of partial pressure or concentration at a given temperature. It considers adsorption of an ideal gas onto an idealized surface. The gas is presumed to bind at a series of distinct sites on the surface of the solid as indicated in Figure 1, and the adsorption ... ref cite book coauthors Masel, Richard title Principles of Adsorption and Reaction on Solid Surfaces ... for the simplest case the adsorption of a single adsorbate onto a series of equivalent sites ... Adsorption Isotherm Kinetic Derivation main Langmuir equation This section ref cite book coauthors Masel, Richard title Principles of Adsorption and Reaction on Solid Surfaces publisher Wiley Interscience ... adsorbate case. The multiple adsorbate case is covered in the Langmuir adsorption model Competitive Adsorption Competitive adsorption sub section. The model assumes adsorption and desorption as being elementary processes, where the rate of adsorption r sub ad sub and the rate of desorption r sub .... At equilibrium, the rate of adsorption equals the rate of desorption. Setting r sub ad sub r sub ... that combined site balance and equilibrium, yields the Langmuir adsorption isotherm math theta A frac ... 2008 11 09 ref This derivation ref cite book coauthors Masel, Richard title Principles of Adsorption ... adsorbed molecule, math N S math are the number of sites available for adsorption. Hence, N, which ... arising due to the indistinguishable nature of the adsorption sites. The Partition function statistical ... off after P reaches P sub 0 sub . Competitive Adsorption The previous derivations assumes ... Masel, Richard title Principles of Adsorption and Reaction on Solid Surfaces publisher Wiley Interscience ... more details
context date September 2008 Expanded bed adsorption EBA is a preparative chromatographic technique which makes processing of viscous and particulate liquids possible. Principle The protein binding principles in EBA are the same as in classical column chromatography and the common ion exchange , hydrophobic interaction and affinity chromatography ligands can be used. ref cite doi 10.1002 elsc.200800027 ref After the adsorption step is complete, the fluidized bed is washed to flush out any remaining particulates. Eluent Elution of the adsorbed proteins is commonly performed with the eluent flow in the reverse direction, that is, as a conventional packed bed, in order to recover the adsorbed solution solutes in a smaller volume of eluent. EBA may be considered to combine both the Removal of Insolubles and the Isolation steps of the 4 step downstream processing heuristic. The major limitations associated with EBA technology is biomass interactions and aggregations onto adsorbent during processing. ref cite doi 10.1016 j.chroma.2007.11.078 ref Where classical column chromatography uses a solid phase made by a packed bed, EBA uses particles in a fluidization fluidized state. Expanded bed adsorption is, however, different from fluidised bed chormatography in essentially two ways one, the EBA resin contains particles of varying size and density which results in a gradient of particle size when expanded and two, when the bed is in its expanded state, local loops are formed. Particles such as whole cells or cell debris, which would clog a packed bed column, readily pass through a fluidized bed. ref cite doi 10.1016 S0167 7799 97 01045 7 ref EBA can therefore be used on crude culture broths or slurries of broken cells, thereby bypassing initial clearing steps such as centrifugation ... as frontal adsorption in a packed bed, rather than as a well mixed continuous flow adsorber. References ... bed adsorption , at Modern Drug Discovery DEFAULTSORT Expanded Bed Adsorption Category Biochemistry ... more details
Protein adsorption refers to the adhesion of proteins to solid surfaces. This phenomenon is an important issue in the food processing industry, particularly in milk processing and wine and beer making. Excessive adsorption, or protein fouling, can lead to health and sanitation issues, as the adsorbed .... However, in some cases protein adsorption is used to improve food quality, as is the case in fining of wines. Protein Adsorption Protein adsorption and protein fouling can cause major problems .... Eng. Chem. Res. year 2001 ref Examples of Adsorption Beer Stone Beer stone is a buildup that forms ... affect product quality by preventing adequate heating of milk. Mechanisms for Protein Adsorption The common trend in all examples of protein adsorption in the food industry is that of adsorption to minerals ... Adsorption and Binding of Protein on clean Homoionic and dirty coated with Fe oxyhydroxides Montmorillonite ... first2 V. last3 Wei first3 A.P. year 1992 title Adsorption of Complex Proteins at Interfaces journal ... Protein adsorption can also occur as a direct result of heating a mixture. Protein adsorption in milk processing is often used as a model for this type of adsorption in other situations. Milk ... them, making it favorable for surface adsorption. Some of the lactoglobulin lg will adsorb ... of the container. File Denatrued Adsorption.gif thumb Mechanism of denaturing protein adsorption Biochemical ... last2 Sakiyama first2 Takaharu last3 Imamura first3 Koreyoshi title Review On the Adsorption of Proteins ... adsorption. ref name Isotherm cite journal last1 Al Malah first1 Kamal last2 McGuire first2 Joseph ... Adsorption Isotherm journal Journal of Colloid and Interface Science volume 170 pages 261 268 ref math ... volume of protein math W a math is the negative of the Gibbs Free Energy of adsorption per unit area ... setting of protein adsorption at temperatures higher than 50 C from a model solution of protein ... Protein Adsorption In The Food Industry Category Biochemistry Category Food industry Category Sanitation ... more details
Iron oxide adsorption is a water treatment process that is used to remove arsenic from drinking water . Arsenic is a common natural contaminant of Water well well water and is highly carcinogenic . Iron oxide adsorption treatment for arsenic in groundwater is a commonly practiced removal process which involves the chemical treatment of arsenic species such that they adsorb onto iron oxides and flocculation create larger particles that may be filtration filtered out of the water stream. The addition of ferric chloride , FeCl sub 3 sub , to well water immediately after the well at the influent to the treatment plant creates ferric hydroxide, Fe OH sub 3 sub , and hydrochloric acid, HCl. 3H sub 2 sub O FeCl sub 3 sub Fe OH sub 3 sub 3HCl Fe OH sub 3 sub in water is a strong adsorbent of arsenate, As V , provided that the pH is low. HCl lowers pH, assuring arsenic adsorption, and the disassociated chlorine oxidizes iron in solution from Fe sup 2 sup to Fe sup 3 sup , which then may bond with hydroxide ions, OH sup sup , thus creating more adsorbent. This adjustment also lowers the pH of the well water, decreasing alkalinity and allowing more cationic species such Fe or As as to exist freely within the flow. Low pH also decreases the solubility of some iron and arsenic species as well as increasing the adsorptive reactivity of arsenate, As V . Additional oxidation of Fe sup 2 sup to Fe sup 3 sup , also referred to as iron II and iron III , is induced by the addition of sodium hypochlorite , NaOCl, at the well head. NaOCl is usually added for disinfection although it may be used in this case towards the objectives of a distribution system free chlorine residual of 1 mg L and the oxidation of aqueous As III to As V , and aqueous iron Fe sup 2 sup to Fe sup 3 sup , which will bond with hydroxide for further adsorption. The filter media usually consists of anthracite , iron manganese oxidizing sand, and garnet sand over support gravel . ref cite title Chemistry of Water Treatment ... more details
a few molecules thick, surface areas of several hundred square meters per gram enable the adsorption ... efficiency over a conventional PSA process. See also Adsorption Gas separation Hydrogen pinch ... Chem stub de Druckwechsel Adsorption nl Pressure swing adsorptie ... more details
Advert date June 2008 Context date October 2009 Vacuum swing adsorption VSA is a non cryogenic gas separation technology. Using special solids, or adsorption chemistry adsorbent s, VSA segregates certain gases from a gaseous mixture under minimal pressure according to the species molecular characteristics and affinity for the adsorbents. These adsorbents e.g., zeolite s form a molecular sieve and preferentially adsorb the target gas species at near ambient pressure. The process then swings to a vacuum to regenerate the adsorbent material. VSA differs from cryogenic distillation techniques of gas separation as well as pressure swing adsorption PSA techniques because it operates at near ambient temperatures and pressures. VSA may actually be best described as a subset of the larger category of PSA. It differs primarily from PSA in that PSA typically vents to atmospheric pressures, and uses a pressurized gas feed into the separation process. VSA typically draws the gas through the separation process with a vacuum. For oxygen and nitrogen VSA systems, the vacuum is typically generated by a blower. Hybrid Pressure swing adsorption VPSA systems also exist. VPSA systems apply pressurized gas to the separation process and also apply a vacuum to the purge gas. VPSA systems, like one of the portable oxygen concentrators, are among the most efficient systems, measured on customary industry indices, such as recovery product gas out product gas in , productivity product gas out mass of sieve material . Generally, higher recovery leads to a smaller compressor, blower, or other compressed gas or vacuum source and lower power consumptions. Higher productivity leads to smaller sieve beds. The consumer will most likely consider indices which have a more directly measurable difference in the overall system, like the amount of product gas divided by the system weight and size, the system ..., March 2001 Adsorption Research, Inc., Absorption is the Solid Solution, http www.adsorption.com publications.htm ... more details
DNA Separation by Silica Adsorption is an important method of DNA separation that is used in novel technologies that use micro channels. The principle behind this type of separation relies on DNA molecules binding to silica surfaces in the presence of certain salts and under certain pH conditions. Why is this method of purification important? Conventional methods for DNA extraction , such as centrifugation with ethanol or preparations using commercial purification kits, cannot be integrated onto microchips because they require multiple hands on processing steps. In addition, they also require large equipment and high volumes of reagents and samples. DNA extraction on microchips provides a fast, cost effective, and effective for high throughput screening , which also has a very small footprint. This new method has useful applications for biosensors , lab on a chip devices, and other new technologies that require rapid, high quality DNA at minimal cost. How does this method of purification work? Before going into great detail, let s first outline the basic steps of this purification method 1. The sample is run through a micro channel br 2. DNA binds to the channel, and all other molecules remain in the buffer solution br 3. The channel is washed of impurities br 4. An elution buffer removes the DNA from channel walls, and the DNA is collected at the end of the channel. A sample this may be anything from purified cells to a tissue specimen is placed into the chip and lysed. The resultant mix of proteins , DNA , phospholipids , etc., is then run through the channel where the DNA is adsorbed by silica surface in the presence of solutions with high ionic strength. The highest DNA adsorption efficiencies are shown to occur in the presence of buffer solution with a pH at or below the pKa of the surface silanol groups. Missing image removed Image DNASepProflie.GIF frame right Example ... 66 2003 . K. A. Melzak, C. S. Sherwood, R. F. B. Turner, C. A. Haynes. Driving Forces for DNA Adsorption ... more details
Adsorption Method for Sampling of Dioxins and Furans AMESA is an automatic system for continuous monitoring of emissions of Polychlorinated dibenzodioxins dioxins and furan s from industrial processes which require official approval in compliance with environmental regulations. ref name mayer2000 cite journal author Mayer J, Linnemann H, Becker E, Rentschler W, Jockel W, Wilbring P, and Gerchel B title Certification of a long term sampling system for PCDFs and PCDDs in the flue gas from industrial facilities journal Chemosphere volume 40 issue 9 11 pages 1025 1027 month May Jun year 2000 accessdate 2008 04 01 doi 10.1016 S0045 6535 99 00349 5 pmid 10739042 ref Applications include refuse incinerators and hazardous material incinerators. Method A sample is continuously extracted from the gas stream being monitored using a titanium probe, which is water cooled to below 70 C. The sample flow rate is automatically adjusted to ensure isokinetic sampling the velocity of gas entering the sampling system is equal to the velocity of the gas in the system under test . The sample gas is drawn through a quartz wool pre filter and then across a cartridge filled with resin, such as XAD resins XAD 2. The sample gas is also cooled to below 5 C to condense and remove water vapour. All system parameters are recorded digitally during sampling. The resin cartridge and the condensate are removed at the end of a monitoring period, and the contents are analysed to determine levels of dioxins and furans. ref name mayer2000 References Refimprove date April 2008 references industry stub Category Chemical tests Category Analytical chemistry ... more details
VPSA may stand for Vacuum Pressure Swing Adsorption technology, a non cryogenic method for gas separation, in some ways similar to Pressure Swing Adsorption technology. Virginia Power Soccer Association See also Adsorption Gas separation Pressure Swing Adsorption disambiguation ... more details
4 and 1 n 0.6. The Freundlich Adsorption Isotherm is mathematically expressed as math frac x m Kp ... temperature. At high pressure 1 n 0 Hence extent of adsorption is independent of pressure But at high ... is not known, such as adsorption of colored material from sugar, vegetable oil etc. Limitation of Freundlich adsorption isotherm Experimentally it was determined that extent of adsorption varies directly with pressure till saturation pressure Ps is reached. Beyond that point rate of adsorption saturates even after applying higher pressure. Thus Freundlich Adsorption Isotherm failed at higher pressure. References Adsorption on heterogeneous surfaces the exponential equation for the overall adsorption ... freundlich adsorption isotherm http www.tutorvista.com content chemistry chemistry iv surface chemistry freundlich adsorption isotherm.php chromatography Category Chromatography es Isoterma de Freundlich ... more details
An adparticle is an atom , molecule , or cluster of atoms or molecules that lies on a crystal surface. The term is used in surface chemistry . The word is a contraction of adsorption adsorbed particle . An adparticle that is a single atom may be referred to as an adatom . Category Surface chemistry physical chemistry stub it adparticella ... more details
A sorption isotherm also adsorption isotherm describes the equilibrium of the sorption of a material at a surface more general at a surface boundary at constant temperature . It represents the amount of material bound at the surface the sorbate as a function of the material present in the gas phase and or in the solution. Sorption isotherms are often used as empirical models, ref name Atkins Peter Atkins Atkins, P. W. , Physical Chemistry , Oxford University Press, 6th ed., 1998, ISBN 0 19 850101 3 ref which do not make statements about the underlying mechanisms and measured variables. They are obtained from measured data by means of regression analysis . The most frequently used isotherms are the linear isotherm , Freundlich isotherm , the Langmuir isotherm , and the Adsorption BET BET model . See also Adsorption Chemisorption Desorption Gibbs isotherm Moisture sorption isotherm References Reflist Chemistry stub Category Physical chemistry Category Surface chemistry de Sorptionsisotherme es Isoterma de adsorci n fa zh ... more details
Sorb may refer to Sorbs , a Slavic ethnic group Sorbus , a genus of trees Sorbus domestica , a species belonging to the Sorbus genus Sorbus aucuparia , a species belonging to the Sorbus genus Sorbus torminalis , a species belonging to the Sorbus genus Sorption , the action of both absorption and adsorption disambig ... more details
PZC may refer to Point of zero charge , a concept relating to the phenomenon of adsorption in physical chemistry Provinciale Zeeuwse Courant , a Dutch newspaper for the region of Zeeland Providence Zen Center , the international headquarters for the Kwan Um School of Zen PZ Cussons , a manufacturer of personal healthcare products and consumer goods disambiguation ... more details
Refimprove date January 2011 BET theory aims to explain the physical adsorption of gas molecule s on a solid ... for monolayer molecular adsorption, to multilayer adsorption with the following hypotheses a gas ... adsorption layer and c the Langmuir theory can be applied to each layer. The resulting BET equation ... and the saturation pressure of adsorbates at the temperature of adsorption, math v math is the adsorbed ... 1 E L RT right 2 math center math E 1 math is the heat of adsorption for the first layer, and math E ... 1.jpg 300px thumb BET plot Equation 1 is an adsorption isotherm and can be plotted as a straight line ... for the calculation of area surface areas of solid s by physical adsorption of gas molecules. A total ... Avogadro s number , math s math adsorption cross section of the adsorbing species, math V math molar ... equation Langmuir theory , but by considering multilayered gas molecule adsorption, where ... act as a single adsorption site for a molecule of the upper layer. 3. The uppermost molecule layer is in equilibrium with the gas phase, i.e. similar molecule adsorption and desorption rates. 4. The desorption is a kinetically limited process, i.e. a heat of adsorption must be provided 4.1. these phenomenon are homogeneous, i.e. same heat of adsorption for a given molecule layer. 4.2. it is E sub 1 sub for the first layer, i.e. the heat of adsorption at the solid sample surface 4.3. the other ... of adsorption is E sub L sub is equal to the heat of liquefaction. 5. At the saturation pressure .... Let us assume that the adsorption rate R sub ads,i 1 sub for molecules on a layer i 1 i.e. formation ... for the adsorption on the layer i 1 and desorption on layer i , respectively. For the adsorptions ... of adsorption, equals to E sub 1 sub at the sample surface and to E sub L sub otherwise. Example ... and usually has an adsorption cross section physics cross section math s math of 0.16 nm sup 2 sup for nitrogen adsorption at liquid nitrogen temperature, is revealed from experimental data ... more details
The sticking probability is the probability that molecules are trapped on surfaces and adsorb chemically. From Langmuir equation Langmuir s adsorption isotherm , molecules cannot adsorb on surfaces when the adsorption adsorption sites are already occupied by other molecules, so the sticking probability can be expressed as follows s s sub 0 sub 1 c where s sub 0 sub is the initial sticking probability and c is the coverage. Similarly, when molecules adsorb on surfaces dissociatively, the sticking probability is s s sub 0 sub 1 c sup 2 sup Although these equations are simple and can be easily understood, they cannot explain experimental results. Their simple explanation is not enough. In 1958, P. Kisliuk ref name kius cite journal last Kisliuk first Paul title The sticking probabilities of gases chemisorbed on the surfaces of solids journal Journal of Physics and Chemistry of Solids year 1957 volume 3 pages 95 101 url http www.sciencedirect.com science article pii 0022369757900549 doi 10.1016 0022 3697 57 90054 9 ref presented an equation that can explain experimental results. In his theory, molecules are trapped in precursor states physisorption before chemisorption . Then the molecules meet adsorption sites that molecules can adsorb to chemically, so the molecules behave as follows. If these sites are not occupied, molecules desorb from the surface pd probability move to the next precursor state pm probability adsorb on the surface chemically pa probability and if these sites are occupied, they desorb from the surface pd probability move to the next precursor state pm probability Then the sticking probability is s s sub 0 sub 1 cK pa pd 1 K pd pa pd When K 1, this equation equals Langmuir equation Langmuir s adsorption isotherm . Notes Reflist References The constitution and fundamental properties of solids and liquids. part i. solids. Irving Langmuir J. Am. Chem. Soc. 38, 2221 95 1916 Cite doi 10.1021 ja02268a002 DEFAULTSORT Sticking Probability Category Physical c ... more details
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